Hairspring assembly for timepieces



Oct. 13, 1936. w. B. EDDISON ET AL HAIRSPRING ASSEMBLY FOR TIMEPIECES 2 Sheets-Sheet 1 Fil ed May 20, 1955 Oct. 13, 1936. w B EDDlSON ET AL 2,057,642

HAIRSPRING ASSEMBLY FOR TIMEPIECES Filed May 20, 1935 2 Sheets-Sheet 2 Patented Oct. 13, 1936 UNITED STATES PATENT OFFICE William Barton Eddison, Ardsley-on-Hudson, and John V. McAdam, Hastings-on-Hudson, N. Y.

Application May 20,

4 Claims.

This invention relates to an improvement in hairspring assemblies, andparticularly to hairspring assemblies for clocks, watches ancl the like.

Heretofore,' as generally constructed, hairspring assemblies have been open to many objections and have varied considerably one from another, especially with respect to angularity between the respective planes of the spiral hairspring and the hub or collet to which the hairspring is secured. Variations of other types have also been largely characteristic of prior hairspring assemblies, among which may be mentioned variations 'in the degree of concentricity between the balance-staffs and the hairsprings.

Hairspring assemblies having variations such as those above mentioned have required so-called leveling and truing operations by expert craftsmen before becoming sufiiciently uniform or otherwise suitable for use in reliable timepieces.

One of the objects of the present invention is to provide a superior hairspring assembly which may be produced at a low cost for manufacture.

A further object is to provide a superior hairspring assembly which, when duplicated, will possess substantially the same characteristics.

Another object of the present invention is to produce a hairpring assembly which will not require careful leveling or truing before becoming suitable for use in timepieces.

A still further object is to provide a construction by means of which parallelism is assured between the plane of a hairspring and the plane of the collet or hub to which it is secured.

Another object of the present invention is to provide simple and effective means for insuring the substantial uniformity in the concentricity of a hairspring and its hub or collet.

With the above and other objects in view, as will appear to those skilled in the art from the following, considered in conjunction with the accompanying drawings and appended claims, the present invention includes all features disclosed therein which are novel over the prior art.

In the accompanying drawings:

Fig. 1 is a face view of one form which a hairspring assembly embodying the present invention may assume;

Fig. 2 is an edge View thereof;

Fig. 3 is a broken sectional view taken on the line 33 of Fig. 1, but on a larger scale;

Fig. 4 is a perspective view of the hub or collet prior to its mounting upon a balance-staff and 1935, Serial No. 22,380

prior to the attachment of a ai sp g thereto;

Fig. 5 is an edge view thereof;

Fig. 6 is a perspective view of another form of hub or collet;

Fig. 7 is a face view of another form of hairspring assembly embodying the present invention;

Fig. 8 is a broken sectional view taken on the line 88 of Fig. 7;

Fig. 9 is a broken face view of still another form of hairspring assembly embodying the present invention;

Fig. 10 is a broken sectional view taken on the line ilk-I0 of Fig. 9; and

Fig. 11 is a broken sectional view taken on the line Il-Il of Fig. 9.

The particular hairspring assembly herein chosen for illustration in Figs. 1 to 5 inclusive, includes a substantially-rectangular mountingmember in the form of a plate-like hub or collet it! formed of brass or other suitable material and provided substantially in its center with a bore ll adapted to receive a balance-staff I2. At one end the collet I0 is grooved by a turning or other suitable operation to provide a hairspring seat l3 which is longitudinally curved in a direction substantially concentrically with respect to the bore H, and extends transversely in a direction parallel to the axis of the said bore.

It may here be noted that hairspring-tails such as 20, as heretofore made, vary considerably both in length and in angle with respect to the hairsprings proper, and are more often than not materially out of plane therewith. Due to these almost inevitable variations, it is preferable to secure the hairspring to the collet by clamping such portion of the former as may be relied upon to be of uniform shape.

Extending outwardly beyond the hairspringseat I3, on the respective opposite sides thereof, are curved clamping-lips l4-l4 adapted to be bent inwardly toward each other, as shown particularly well in Fig. 3, to clamp a spirallycurved portion l5 of a spiral hairspring l6 against the hairspring-seat 13 of the collet l0 before referred to. Preferably, and as shown, the said hairspring I6 is formed of wire having substantially-rectangular form in cross-section, though obviously, wire of other cross-sectional form may be employed. The hairspring shown may be conveniently produced by employing an initially-round wire and flattening the same on its respective opposite sides by a suitable rolling operation.

The dimension A (Fig.4) from the center of the bore II to the outer edges of the clamping-lips I4 exceeds the dimension B from the center of the said bore to the opposite curved edge I! of the hub or collet I0, despite which the bore ll substantially coincides with the center of gravity of the collet by reason of the fact that the latter is wider at its edge ll than it is at the outer edges of the clamping-lips l4. From the proportion ing just described, the collet [0 possesses substantial balance both statically and dynamically.

Centrally of its edge l1, the collet i0 is formed with a relatively-deep radial notch l6 having its inner terminal-wall closely approaching the bore H but separated therefrom by a relatively-thin tie-web l9 which will readily stretch or fracture when the collet i0 is staked upon the balancestafl l2.

It will be noted that the usual tail 20 at the inner end of the hairspring I6 (formed as a result of the operation of coiling the hairspring itself) occupies the space between the adjacent convolution of the hairspring and the adjacent sloping side face of the collet In.

In assembling the unit, the portion l5 of the spiral-reach of the hairspring I6 is placed against the hairspring-seat l3, and the respective clamping-lips |4|4 are simultaneously bent toward each other by suitable dies or tools so that the flat inner face of the said portion l5 of the hair spring is clamped tightly against the hairspringseat l3, thus assuring that the hairspring, considered as a whole, will extend in a plane perpendicular to the axis of the bore H and the balance-staff l2.

In the outer corner of each of the clampinglips l4|4 is shown a shallow groove 2| created by the action of the tools or dies in bending the said clamping-lips toward each other, as described.

After the hairspring l6 and its hub or collet ill have been assembled together, as above described, the collet may be driven over a balance stafl such as l2 so as to become rigidly attached thereto. Inasmuch as it is preferable to have the diameter of the bore II in the collet slightly smaller in diameter than the diameter of the balance-staff l2, when the collet is forced over the staff l2 as just above described, the tie-web l9 will stretch and in most instances fracture as indicated in Fig. 1. By leaving the tie-web l9 interposed between the inner end of the notch l8 and the bore ll, instead of extending the said notch entirely through to the said bore, such burring of the latter as might cause the canting of the collet on the balance-staff is avoided.

Furthermore, by means of the tie-web IS, the collet, together with the hairspring, may, after being mounted on the balance-staff, be oriented with respect thereto, as may be required to set the beat of the watch, clock, or other time-instrument in which the unit is mounted. Despite the fact that the tie-web I!) may be fractured in forcing the collet over the balance-staff, the grip of the former upon the latter is sufiicient to retain both in relatively-fixed positions under normal operating conditions, while permitting relative adjustment between them for the purpose described.

Inasmuch as the hairspring-seat l3 substantially conforms in lengthwise direction to the curvature of the spiral portion I5 of the hairspring, the latter will be substantially concentric with the bore H and hence with the balancestaif l2, when the said portion I5 is snugly pressed against the said seat. By the arrangement just described, it is unnecessary to employ the services of expert craftsmen to bend the hairspring to cause it to centrally locate itself with respect to the bore ll.

Due to the fact that laterally the hairspringseat l3 extends parallel to the axis of the bore H, the plane of the hairspring considered as a whole will be truly perpendicular with respect to the axis of the balance-stair l2, owing to the fact that the said hairspring is firmly clamped against the said seat l3. Thus, it is not necessary to employ the services of expert craftsmen to bend the hairspring laterally in order to effect the perpendicular relationship just referred to.

In Fig. 6 is shown a hub or collet Ill having parallel side edges and provided with a bore ll for the reception of a suitable balance-staff. Like the collet It], the collet I0 is provided with a radial notch l8 extending inwardly from its curved edge I1 and having its inner terminal separated from the bore I l by a fracturable tieweb l9.

Also like the collet ID, the collet I0 is provided with a hairspring-seat extending longitudinally in a direction substantially-concentrically with respect to the bore H and while the said seat may be viewed in effect as one, it is divided into three sections l3, l3 and [3 by forming the collet with two relatively-shallow notches 22-22. clamping-lips M, the collet I0 is formed on each of the opposite sides of its hairspring-seat with a clamping-lip which is divided by the said notches into three sections l4, N and M, each set of which is adapted to be bent toward the other set to clamp a portion of the spiral-reach of the hairspring against the hairspring-seat.

In Figs. 7 and 8 is shown a collet 23 formed substantially centrally with a bore 24 receiving a balancc-staff 25. Like the collets before described, the collet 23 is formed in one end with a relatively-deep notch 26, the inner terminal of which closely approaches the bore 24 and is separated therefrom by a relatively-slender tie- Web 21.

While it is preferred to grip a hairspring by means of a portion of its spira1reach, the collet 23 now being described is designed to grip the offsetting tail 28 of a hairspring 29. By careful manufacturing methods, the tail 28 may have a carefully predetermined angular relationship with respect to the hairspring 29 proper, and may be seated against a flat hairspring-seat 36 constituting the bottom of a groove 3| formed in the end of the collet 23 opposite the notch 26 therein. Flanking the respective opposite sides of the hairspring-seat 30 are a pair of complementary clamping-lips 32--32 adapted to be bent inward- 1y toward each other to force the flat inner face of the tail 28 of the hairspring 29 into surface engagement with the hairspring-seat 30 over substantially all of the area thereof.

In Figs. 9 to 11 inclusive is shown a collet 33 provided with a concave hairspring-seat 34 interrupted by a notch 35 and flanked on either side by complementary clamping-lips 36-36, also interrupted by the notch 35 just referred to.

The clamping-lips 36-36, above referred to, are bent inwardly toward each other in any suitable manner to clamp the flat inner face of the tail 3'! of a hairspring 38 against the hairspringseat 36 throughout substantially the entire surface area thereof.

The tail 3'! may be formed straight at a carefully predetermined angle with respect to the Instead of having continuous hairspring 38, if desired, as the tail 28 of Figs. 7 and 8 and the central portion of the said tail may be flexed inwardly by an instrument acting through the notch 35 in the collet 33 prior to the bending of the clamping-lips 36-36.

Opposite the notch 35, the collet 33 is formed with a relatively-deep notch 39 separated from the bore 40 of the collet by a slender tie-Web M.

It will be noted that in all of the forms of the present invention herein shown, the portion of a hairspring chosen for direct attachment to the collet is engaged with and conformed to the hairspring-seat of the latter over a large surface area thereof, rather than having a mere line contact therewith.

Thus, by providing a seat of predetermined character and clamping a portion of the hairspring against a two-dimensional surface thereof, a hairspring assembly may be provided in which the hairspring has the desired degree of concentricity and planar accuracy.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are therefore to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

We claim:

1. In a hairspring assembly, the combination with a balance-staff; of a spiral hairspring; and a mounting-member secured to and extending laterally from the said balance-staff and having an outwardly-facing hairspring-seat longitudinally-curved substantially-concentrically with respect to the said balance-staii and extending transversely in a direction substantially-parallel therewith, the said mounting-member also having a staff-receiving bore and a notch separated from the said bore by a fracturable tie-web; a portion of the spiral-reach of the said hairspring being firmly seated against the hairspring-seat of the said mounting-member.

2. In a hairspring assembly, the combination with a balance-staff; of a spiral hairspring; and a mounting-member laterally extending from the said balance-stafi and having the said spiral hairspring attached thereto; the said mountingmember being provided with a bore for the reception of the said balance-staff and with a notch separated from the said bore by a relativelyslender tie-web.

3. In a hairspring assembly, the combination with a balance-staff of a non-circular mountingmember secured to and extending laterally from the said balance-staff and having a relativelyshort outwardly-facing hairspring-seat having a terminal-edge at each of its respective opposite ends, the said mounting-member also having two complementary clamping-lips extending substantially-perpendicularly with respect to the said balance-staff and respectively located on opposite sides of the said hairspring-seat and bent toward each other; and a spiral hairspring having its inner portion in two-dimensional surface-contact with the hairspring-seat of the said mountingmember and clamped in place against the same by the said bent complementary clamping-lips and substantially conforming thereto, the said hairspring projecting from one of the terminaledges of the said hairspring-seat.

4. In a hairspring assembly, the combination with a balance-staff; of a non-circular mountingmember secured to and extending laterally from the said balance-staff and having a relatively-short outwardly-facing longitudinally-curved hairspring-seat of segmental form, the said hairspring-seat having a terminal-edge at each of its respective opposite ends, the said mountingmember also having two complementary clamping-lips extending away from the said balancestaff and respectively located on the opposite sides of the said longitudinally-curved hairspringseat and bent toward each other; and a spiral hairspring having its inner portion in two-dimensional surface-contact with the curved hairspring-seat of the said mounting-member and clamped in place against the same by the said bent complementary clamping-lips and substantially conforming to the said hairspring-seat, the said hairspring projecting from one of the terminal-edges of the said hairspring-seat.

WILLIAM BARTON EDDISON. JOHN V. McADAM. 

